Process of dyeing acrylonitrile textile by cuprous ion technique



PROCESS OF DYEING ACRYLONITRILE TEXTILE 1 1 BY CUPROUS ION TECHNIQUE Francis W. Glaze, Jr., Kennett Square, Pa., and Stanley B. Speck, Wilmington, Del., assignors to E. I. du Pont de Nemours & Company, Wilmington, Del., :1 corporation of Delaware Application October 20, 1952, Serial No. 315,834

9 Claims. (c1. s-ss t No Drawing.

This invention relates to a chemical process. More particularly, it relates to a process for dyeing a textile produced from a polymer of acrylonitrile.

By the term textile produced from a polymer of acrylonitrile is meant a filament or fiber or the like formed by extrusion of a polymer of acrylonitrile such as is illustrated in U. S. Patent No. 2,436,926 to R. A. Jacobson, dated March 2, 1948, and also the yarn, staple, fabric and the like produced therefrom. The term polymer of acrylonitrile [is intended to include any polymer of acrylonitrile, including polyacrylonitrile (i. e., the homopolymer), wherein the acrylonitrile component constitutes about 40% or more of the polymer molecule calculated as CH2 CH-CN. Among the compounds that may be copolymerized with acrylonitrile may be mentioned vinyl chloride, 2-vinyl pyridine, 4-vinyl pyridine, S-ethyl- 2-vinyl pyridine and 2- or 4-vinyl quinoline. polymeric materials are shown in U. S. Patent No. 2,491,471 to H. W. Arnold, dated December 20, 1949. Other materials, such as plasticizers and modifiers, may also be present.

Thedifliculty of dyeing a synthetic textile produced from a polymer of acrylonitrile is well known. One method which has been developed is known as the cuprous ion technique. According to this procedure, dyes, generally acid wool dyes, are applied from an aqueous solution containing cuprous ions. These ions are produced in situ from copper salts by means of reducing agents. The reducing agent must be powerful enough to reduce copper to the cuprous state. It must not destroy the dyestutf. It must reduce the copper at approximately the same rate as it is absorbed by the fiber to avoid deposition of metallic copper in the dye bath. Among the reducing agents which have been adapted to the process may be mentioned the reducing sugars, such as glucose and fructose, sucrose, which hydrolyzes to a reducing sugar under the reaction conditions, sodium and zinc formaldehyde sulfoxylates, hydroxyl amine, furfural and a glyoxal of the formula:

R-ii-ii-H wherein R represents hydrogen or lower alkyl. The process is discussed in detail in the American DyestutfReporter, volume 41, No. 2, pages 39-43 (January 21, 1952). l t 3 In many cases employing this technique, it has been found necessary to operate at temperatures well above boiling in order to obtain a dye of adequate intensity. The problem is particularly acute in the dyeing of textiles produced from a highly-drawn polymer. Where temperatures above boiling are involved, it is necessary to modify conventional equipment to permit operation under pressure.

In accordance with the present invention, it has been found that when an acid dye is applied to a textile produced from a polymer of acrylonitrile by the cuprous ion technique its intensity is greatly increased by the pres- Such co-. 1

r6 CC ence in the dye bath of stable water-soluble salts of heavy metals of the group consisting of vanadium, molybdenum and tungsten.

The following examples are cited by way of illustration. They are not intended to limit the invention in any manner. In each example, the percentages of dyebath components are based on the weight of fiber to be dyed. In each instance, the dyeing is conducted by immersion for two hours at the boil, except for temperature used in Example I, using a 50:1 ratio of dyebath to fabric.

. Example I A dyebath of the following composition is prepared:

0.3 ammonium vanadate 9.0% aqueous glyoxal solution (30% glyoxal) 5.0% CuSo4.5H2O

1.2% of the blue dye of Prototype 12 0.9% of the red acid dye of C. I. 176

2.0% of the yellow quinoline dye of C. I. 802 0.5 wetting agent (alkyl aryl sodium sulfonate) A swatch of a fabric of polyacrylonitrile staple fiber, having a draw ratio of 4X (i. e., the drawn length is four times that of the undrawn length) is dyed in this bath at 208 F. A medium brown dyeing is obtained.

1 Using a dyebath similar in all respects to that described above except that no ammonium vanadate is included produces a weak, dull violet dyeing when the same dyeing procedure is followed.

Example II A dyebath is prepared with a composition as follows:

0.25% sodium tungstate 10.0% fructose 3.0% CuSO4.5H2O

2.0% of the red acid dye of C. I. 176.

A swatch of the fabric described in Example I is dyed in this bath. A bright red coloration results.

Using a dyebath similar in all respects to that described above except that no sodium tungstate is included, produces a light pink stain.

xample III A dyebath, having a composition as follows is prepared:

0.2% ammonium vanadate 3.0% aqueous glyoxal solution (30% glyoxal) 2.0% CuSO4.5HzO

2.0% of the blue acid dye of Prototype 12.

A swatch of a fabric of 8 drawn polyacrylonitrile continuous filament fiber is dyed in this bath. A light blue dyeing is obtained.

Practically no color at all is obtained when the ammonium vanadate is not included in the dyebath.

Example IV .The following dyebath is made up:

0.2% ammonium molybdate 10.0% sucrose 4.0% CUSO4.5H2O

2.0% of the red acid dye of C. I. 176

0.5% wetting agent (polyoxyethylene ether of a fatty alcohol) A swatch of the fabric described in Example I is dyed in this bath. A bright red coloration results.

Using a dyebath similar in all respects to that de scribed above except that no ammonium molybdate is included produces only a light pink stain.

. w. .3 Example V A dyebath of the'followin'g composition is made up:

0.25% ammonium vanadate 4.5% pyruvic aldehyde 4.0% CUSOLSHZO 1.2% of the blue dye of Prototype 12 0.9% of the red dye of C. I. 176 2.0% of the yellow quinoline dye of C. I. 802 0.5% wetting agent (alkyl aryl sodium sulphonate) A swatch of the fabric describe d in Example I is dyed in this bath. Apleasing brown shade is obtained. Similar results are obtained when the pyruvic aldehyde is re placed by 6.0% dihydroxy acetone.

Using a dyebath similar in all respects to that described above except that no ammonium vanadateis included produces a weak violet shade with the same dyeing procedure. s

The optimum dyebath temperature will. vary widely. It will be a function of the particular dye, the particular fabric and the reducing agent employed. For any particular combination, this figure can he arrived at cm pirically. Temperatures as low as 206 F. have been found satisfactory. The upper temperature is limited only by the softening point of the textile and deterioration point of thedye. Dyeing at the boil is preferred. In every case, use ofthe water-soluble heavy metal salt, as taught by the presentinvention, permits a more intense dyeing at any chosen temperature. Thus, it is possible by employing the process of the present invention to obtain satisfactory deyings'at lower temperatures than was hitherto pos siblc. In many instances, this means that a dyeing can be satisfactorily obtained in conventional type 'equipment rather than in a special, pressurized vessel.

' The dyes useful in this process are the aciddyes, i. e., those which are useful in the dyeing of wool. Among those which are particularly suitable are those which contain the acid sulfinic, sulfonic, or carboxylic groups.v It is essential that the dyebath be maintained acid. A pH between 4.5 and 3 is preferred. A pH lower than 3 is operable but is normally avoided because of slower dyein'g rate. Alkali may be used to raise the pH where desired. A pI-I as high as 5 is operable. While the nature of the acid employed in the acidification is not critical, a mineral acid such as sulfuric is prefeired. Hydrochloric is generally to be avoided due to corrosion problems. ;The quantity of acid is largely governed by the pH desired.

7 Where the dyeings are performed in an aqueous medium above 212 F., it is necessary to employ pressure equipment. In general, autogenous pressures are sufli cient. Higher-pressures may be used, limited only by the strength of the applying apparatus, without deleterious effects. Any conventional process of application, such as package dyeing, padding and printing may be used. A

The percentages of the various components of the dyes bath may vary over a wide range depending upon the particular dye employed and the intensity of coloration desired. Thepercentage of the reducing agent necessary will be governed by the amount of cuprous' ion employed.

scribed invention will be apparent to those skilled in the some light shades, but is generally not suitable for strong shades. Above 2.5 weight percent of cuprous ion, a dulling is observed.

The heavy metal salt, as taught by the present inven tion, may be any water-soulble salt of a metal from the group consisting of vanadium, molybdenum or tungsten. The ammonium salt is preferred; sodium and potassium salts are suitable. Mixtures of these various salts may also be used. A concentration of about 0.2% based upon theweight of the textile has been found to be satisfa'c tory in many instances. Higher concentrations, up to as much as 1.0%, are operable without deleterious effects. 0.3% is considered suflicient for most purposes.

While the invention is particularly of value in the dyeing of a textile produced from a polymer of acrylonitrile with a high draw ratio, it is applicable as well to such a textile of low or intermediate draw ratio. Conventional dye-bath wetting agents may be employed. The nonionic variety, such as the polyoxyethylene ether of a fatty alcohol is preferred. However, as indicated in Example I, ionic materials are useful in this respect. I

Many other modifications within the spirit of thede art without a departure from the inventive concept.

What is claimed is: I l. A process which comprises the application of an acid dye to a textile produced from a polymer of acryl'o nitrile in the presence of cuprous ions and a compound of the class consisting of the non-complex vanadate, moi

lybdate and tungstate sait of ammonium and an alkali metal. 7 V I g v 2. The process of claim 1 wherein the textile comprises p'o'lyacrylonitrile. V p I v 3. The process of claim 1 wherein the Water-soluble salt is the atiimonium salt. i

4. The process of claim 1 wherein the dye is applied at the boil.

5; A process which comprises the application ofan acid dye by a cuprous ion technique to a textile produced from a polymer of acrylonitrile wherein a compound of the class consisting of the non-complex vanadate, molyb date and tungstate salt of ammonium and an alkali metal is present in the dyebath.

The process of claim 5 wherein the cuprous ion is produced from copper sulfate in the presence of glyoxal and the water soluble salt is ammonium vanadate. I

7. The process of claim 5 wherein the cuprous ion is 7 produced from copper sulfate in the p'res'enceof fructose Where copper salts are present in amounts to provide 0.5.

agent (both based on the weight of the fiber to be dyed).

A copper ion strength below this range may be used for andjthe water-soluble salt is sodium tungstate.

8. The process of claim 5 wherein the cuprous ion is produced from copper sulfate in the presenceof sucrose and the water-soluble salt is ammonium molybate.

\ 9. The process of claim 5 wherein the cuprou's ion is produced from copper sulfate in the presence of pyruvic aldehyde and the water-soluble salt is ammonium vanadate.

References Cited in the file of this patent Amer. Dyestuff Reporter for November 12, 1951, p. 750. r v

Amer. Dyestufl Reporter for February 4, 1952,- pp. P75, P76, P77.

Tech. Bulletin by Du Pont, vol. 7, No. 1', for March 1951, pp. -47. 

1. A PROCESS WHICH COMPRISES THE APPLICATION OF AN ACID DYE TO A TEXTILE PRODUCED FROM A POLYMER OF ACRYLONITRILE IN THE PRESENCE OF CUPROUS IONS AND A COMPOUND OF THE CLASS CONSISTING OF THE NON-COMPLEX VANADATE, MOLYBDATE AND TUNGSTATE SALT OF AMMONIUM AND AN ALKALI METAL. 